Estrutura e diversidade do locus rfb em bactérias do gênero Leptospira e sua associação com a classificação sorológica

• Ano de defesa: 2023
• Autor(a) principal: Ferreira, Leonardo Cabral Afonso
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte; Brasil; UFRN; PROGRAMA DE PÓS-GRADUAÇÃO EM BIOINFORMÁTICA
• Palavras-chave em Português: Leptospirose; Locus rfb; Lipopolissacarídeos; CNPQ::CIENCIAS BIOLOGICAS
• Link de acesso: https://repositorio.ufrn.br/handle/123456789/52699

Leptospirosis is considered a globally important zoonosis due to its widespread distribution and virulence, affecting both humans and commercially important animals. It is caused by pathogenic bacteria of the genus Leptospira and phylum Spirochaetes, and contamination occurs through direct or indirect contact with the contaminant agent present in the environment, such as urine from infected animals or contaminated water and soil. The genus has 68 species that can be grouped into two major groups according to their lifestyle: pathogenic and saprophytic. In addition to taxonomic classification, samples of these genera can be classified based on their antigenic characteristics into serogroups and serovars. Serological classification is of great relevance in the fields of epidemiology and clinical analysis, but the methods used for this classification are laborious, require infrastructure and specialized labor, and take days to obtain results. In this study, we aimed to find genetic patterns associated with the serological classification of Leptospira bacteria by analyzing the genetic composition of the rfb locus and proposing methods that allow for the classification of Leptospira samples at the serogroup level. To do this, we used genomic data from 67 species classified into 27 serogroups, which are distributed in 722 samples available in public databases. We identified the genes that are part of the rfb locus through orthologous groups in samples that contained the intact rfb locus in a single contig. We used a hierarchical clustering method to group samples with similar genetic profiles of the rfb locus. This analysis made it possible to contemplate the diversity of the genetic composition profile of the rfb locus in the genus Leptospira and to observe correspondence between serogroup classification and the groups formed by hierarchical clustering. The generated clustering suggests the classification of samples into six large classes that, in addition to presenting serological affinity, share similarities in the genetic composition of the rfb locus. It was observed that samples of the same serogroup share similarities in the genetic composition of the rfb locus. Additionally, it was possible to verify the existence of different gene blocks that may be conserved in samples belonging to different species and serogroups. It is presumed that different combinations of these gene blocks result in the synthesis of different O-antigen structures of lipopolysaccharides and consequently different serogroups. This study allows for the suggestion of molecular markers that allow for the use of molecular strategies for the serological identification of Leptospira.